Amphiphilic co-networks can serve as a means to encapsulate and thereby immunoisolate implantable biologically active moieties. Generally, amphiphilic co-networks comprise hydrophilic and hydrophobic polymers that can swell in both polar and non-polar solvents. Additionally, amphiphilic networks and/or co-networks can be used to produce polymer films that swell in both polar and non-polar solvents. Accordingly, films made from amphiphilic polymer networks and/or co-networks have been found to be desirable in the production of various articles including, but not limited to, contact lenses.
One problem associated with the synthesis of amphiphilic co-networks is how to overcome the thermodynamic incompatibility of the hydrophilic and hydrophobic constituents that will make up the amphiphilic co-network, and to unite two incompatible pre-polymers and/or polymers into a bi-continuous/bi-percolating construct. Typically, crosslinking of such systems is carried out in homogeneous solution in a common solvent at low pre-polymer and/or polymer concentrations, followed by the addition of a suitable crosslinker (i.e., by dissolving the two pre-polymers which are generally incompatible in their dry states). While this method yields uniform co-networks, the removal of the common solvent is accompanied by massive shrinkage, which renders the method technically impractical. Also, the dimensional stability of such co-networks is poor, the surface properties are hard to control, and the co-networks (or products formed therefrom) are fragile and difficult to manipulate.
Thus, there is a need in the art for reliable synthesis routes for amphiphilic co-networks. Specifically, desirable synthesis routes would include those that permit the control of one or more chemical and/or physical properties of amphiphilic co-networks. Also of interest are synthesis routes for amphiphilic co-networks that produce amphiphilic co-networks that are suitable for use in medical (e.g., cell encapsulation), biological and ophthalmic uses.